%从价税对供求的影响
\begin{tikzpicture}
\begin{axis}[
	extra description/.code={\node[below left] at (axis cs:2,0) {$O$};},
	xmin=2,
	xmax=11,
	ymin=0,
	ymax=11,
	extra x ticks={
		4.167,
		5.625
	},
	extra x tick labels={
		\tiny{$Q_{\tau}$},
		\tiny{$Q^*$}
	},
	extra y ticks={
		3.5,
		4.375,
		5.833
	},
	extra y tick labels={
		\tiny{$P_{\tau}$},
		\tiny{$P^*$},
		\tiny{$P_c$}
	},
	extra x tick style={tickwidth=0},
	extra y tick style={tickwidth=0},
	xlabel style={below},xlabel=\small$Q$,
	ylabel style={left},ylabel=\small$P$,
	samples=40,
	domain=2:11
]
\addplot[gray,very thin] coordinates {(0,4.375) (5.625,4.375) (5.625,0)};
\addplot[gray,very thin] coordinates {(0,5.833) (4.167,5.833) (4.167,0)};
\addplot[gray,very thin] coordinates {(0,3.5) (4.167,3.5)};
\addplot[draw=red,ultra thick,domain=2:10] {0.6*x + 1};			%S
\addplot[draw=blueL,ultra thick] {10 - x};				%D
\addplot[draw=blue,ultra thick] {6 - 0.6*x};	%Dt
\addplot[redL,text=red,decorate,decoration={brace,mirror,amplitude=5pt},xshift=-2pt] coordinates {(4.167,5.833) (4.167,3.5)}
	node [fill=white,midway,inner sep=0pt,left=5pt] {\tiny$\tau \cdot P_{\tau}$};
\draw (axis cs:10.5,1) node[blue,below] {$D$};
\draw (axis cs:8,1) node[blue,below] {$D_{\tau}$};
\draw (axis cs:10,7) node[red,above] {$S$};
\draw (axis cs:5.8,4.375) node[right] {\tiny$E^*$};
\draw (axis cs:4.3,3.5) node[right] {\tiny$E_{\tau}$};
\addplot[only marks,forget plot,black,mark options={mark size=1.25pt,fill=white},mark=*] coordinates {
	(5.625,4.375)
	(4.167,3.5)};
\end{axis}
\end{tikzpicture}
